Accurate estimation of the time-to-contact between a vehicle and obstacles is an important component in autonomous driving and computer vision-based driving assistance. Using computer vision techniques to provide assistance while driving, instead of mechanical sensors, allows for the use of the information that is recorded for use in estimating vehicle movement to also be used in estimating ego-motion identifying lanes and the like, without the need for calibration between sensors as would be necessary with mechanical sensors. This can reduce the cost of the arrangements provided to provide time-to-contact estimates and maintenance that may be required therefor.